A third of the permanent snow and ice of New Zealand’s Southern Alps has now disappeared, according to our new research based on National Institute of Water and Atmospheric Research aerial surveys. Since 1977, the Southern Alps’ ice volume has shrunk by 18.4 km3 or 34%, and those ice losses have been accelerating rapidly in the past 15 years.

The story of the Southern Alps’s disappearing ice has been very dramatic – and when lined up with rapid glacier retreats in many parts of the world, raises serious questions about future sea level rise and coastal climate impacts.

The Southern Alps’ total ice volume (solid line) and annual gains or losses (bars) from 1976 to 2014 in km3 of water equivalent, as calculated from the end-of-summer-snowline monitoring programme.

Glaciers are large-scale, highly sensitive climate instruments, which in an ideal world we would pick up and weigh once a year, because their fluctuations provide one of the clearest signals of climate change.

A glacier is simply the surplus ice that collects above the permanent snowline where the losses to summer melting are less than the gains from winter accumulation. A glacier flows downhill and crosses the permanent snowline from the area of snow gain to the zone of ice loss. The altitude of this permanent snowline is the equilibrium line: it marks the altitude at which snow gain (accumulation) is exactly balanced by melt (ablation) and is represented by the end-of-summer snowline.

Tasman Lake, photographed in March 2011. (Trevor Chinn)

In 1977, one of us (Trevor Chinn) commenced aerial photography to measure the annual end-of-summer snowline for 50 index glaciers throughout the Southern Alps.

These annual end-of-summer surveys have been continued by the National Institute of Water and Atmospheric Research (NIWA). We then use the NIWA results to calculate the annual glacier mass balance and hence volume changes of small to medium sized glaciers in the Southern Alps. Small to medium glaciers respond quickly to annual variability of weather and climate, and are in balance with the current climate.

Not so the twelve largest glaciers: the Tasman, Godley, Murchison, Classen, Mueller, Hooker, Ramsay, Volta/Therma, La Perouse, Balfour, Grey, and Maud glaciers. These have a thick layer of insulating rocks on top of the ice lower down the glaciers trunk. Their response to new snow at the top is subdued, and take many decades to respond.

Up until the 1970s, their surfaces lowered like sinking lids maintaining their original areas. Thereafter, glacial lakes have formed and they have undergone rapid retreat and ice loss.

The Rolleston index glacier in the Southern Alps of New Zealand, showing the accumulation area where fresh clean snow gain occurs above the end-of-summer snowline, and the area of melting ice below. Here, a negative balance year in 2009 shows a higher end-of-summer snowline revealing underlying old snow. (Trevor Chinn)

To come up with our calculations, we have used the snowline survey data plus earlier topographic maps and a GPS survey of the ice levels of the largest glaciers to calculate total ice-volume changes for the Southern Alps up until 2014.

Over that time, ice volume had decreased 34%, from 54.5 km3 to 36.1 km3 in water equivalents. Of that reduction, 40% was from the 12 largest glaciers, and 60% from the small- to medium-sized glaciers.

These New Zealand results mirror trends from mountain glaciers globally. From 1961 to 2005, the thickness of “small” glaciers worldwide decreased approximately 12 metres, the equivalent of more than 9,000 km3 of water.

Global Glacier Thickness Change: This shows average annual and cumulative glacier thickness change of mountain glaciers of the world, measured in vertical metres, for the period 1961 to 2005.(Mark Dyurgerov, Institute of Arctic and Alpine Research, University of Colorado, Boulder)

Martin Hoelzle and associates at the World Glacier Monitoring Service have estimated estimate the 1890s extent of ice volume in New Zealand’s Southern Alps was 170 km3, compared to 36.1 km3 now. That disappearance of 75-80% of Southern Alps ice is graphic evidence of the local effects of global warming.

Further large losses of ice in the Southern Alps have been projected by glaciologists Valentina Radic and Regine Hock, suggesting that only 7-12 km3 will remain by the end of the 21st century. This is based on regional warming projections of 1.5°C to 2.5°C. This represents a likely decimation of ice cover of the Southern Alps over two centuries because of global warming.

And where does all this melted glacier ice go? Into the oceans, thus making an important contribution to sea level rise, which poses a serious risk to low-lying islands in the Pacific, and low-lying coastal cities from Miami in the US to Christchurch in NZ.

The disappearing ice story calls for robust effective climate policy to moderate effects on our landscape and coasts, otherwise future generations will have little of New Zealand/Aotearoa’s “long white cloud” alpine ice left to enjoy.

I am not sure how many people rely on summer ice melt for their water supplies but its most probably a fairly high number. At least NZ still gets a lot of rainfall and will do so in the future but it will be on the west coast and we live on the east. I think we will have to dam valleys on the west coast and siphon it to the east to keep people alive. It would also keep the environment and farmers going. The next thirty years are going to be very interesting. http://www.climateoutcome.kiwi.nz/drought.html

Andy, please supply some references from science to support your personal “fairly accurate assessment” you made? “I think I can make a fairly accurate assessment that 0 people rely on snow melt from glaciers for their water supply in NZ”.
As otherwise it is simply you personal opinion.

Thomas, does the Coromandel Glacier provide you with water?
I am planning to live in the area downstream of the Godley Glacier. I am pretty sure our water suppl,y doesn’t come from the glacier. Some may come from snowmelt, but it isn’t the glacier melting.

Sorry I don’t have a scientific paper to back up my claims.
Maybe I can get a grant to write one.

I don’t think you will get many backers. If the glaciers disappear the Waimak fades to a trickle, precious Christchurch groundwater disappears, and with sea level rise, there is also the added risk of salt water intrusion. Christchurch is not unique as a coastal city reliant on groundwater derived from glacial melt.

“The main source of the Waimakariri is a glacier at the head of the White river, having its origin in the snow-fields on the northern slopes of Mount Grreenlaw, 4162 feet above the sea-level. After receiving several tributaries of glacier origin, the White river, as it has been named from the peculiar colour of its water, generally thick from finely triturated matter, originating from the action of the glaciers on their rocky bed, unites five miles from its origin with the northern Waimakariri, which having a south-south-east course, meets the former at a right angle.”

“Christchurch (population 340 000) has one of the best water supplies in the world. The supply comes from groundwater, is of extremely high quality, and requires no treatment.

The groundwater system that provides this water is dominated in the west by gravels (possibly up to 350 m thick) and sands deposited by the Waimakariri River. Beneath Christchurch, and to the east, is a succession of alternating gravel and marine deposits.”

Tony I think that it is going a step too far to say that the Waimakariri will dry to a trickle. I don’t see that said as much in the reports – even though it does state that the main source is the glacier. The situation is that as the glacier melt slows – that will be replaced by rainfalls and snowfalls, much as it is today. The ice won’t be there, and yes – there has been some accumulation over the centuries, which with global warming has increased the inflow into the rivers. So the rivers flowing today are actually greater than they have been in the past (boosted by glacial melt). Were there no global warming, then the inflows would be as they have always been essentially from spring/summer melt and rainfall and snowfall in the catchment areas. There is the possibility that the inflows will be greater due to the increase in precipitation from warmer atmosphere.

If what you say is true, then the Selwyn, which has no glacial origin should run year round as well. However, the Selwyn, certainly over most summer months almost disappears. If the Waimak were to behave in a similar fashion, then I expect most of the things we take for granted will be adversely affected, I doubt if crop irrigation in peak summer months when it is most needed will be possible for example and under such conditions with more extreme droughts then there will be tough times ahead.

If what you say is true, then the Selwyn, which has no glacial origin should run freely year round. However, the Selwyn, certainly over most summer/autumn months runs dry. If the Waimak were to behave in a similar fashion, then what effect would that have on water tables?

Christchurch has had the occasional dry year, where water tables were so low that rationing had to be implemented. Now imagine the Waimak dry for up to half the year, and perhaps so on a regular basis, what effect would that have on water tables?

I’m with Kiwipoet, but this forum is mainly preaching to the converted excluding AndyS. What we need is better information flow to the public and this is where perhaps the media and government are failing miserably. For example, why is Ken Ring allowed a regular commentary to the news media but not someone like Jim Salinger, or even Gareth.

Andy, in many parts of the world glaciers cause well needed averaging of river flows which are sustained through dry summer months from melt waters. With global warming progressing not only do the glaciers retreat and eventually disappear but the snow level is rising with a rapid decline in snow covered land mass. Rainfall then rushes down-stream in flooding events with water being wasted rather than accumulating as snow and ice to sustain summer melts and summer dry periods.
California and the US South West is suffering. India and China will feel the change. And the dry regions of NZ to the East of the divide on the southern alps are at risk too.

Other potential impacts of glacial melting include greater risk of avalanches and flooding,4 reduced hydropower capacity during dry seasons, and a decline in the amount of water available for irrigation.

Bob I questioned Jim on this very point when I last met him at last years Eco Conference. Apparently NIWA has run projections on inflows into the Hydro lakes and inflows will remain much the same or increase with increased precipitation events. The precipitation falls on both sides – as evidenced by the fact that snow is on both sides of the mountains. The rain shadow area is further East – MacKenzie Basin etc.

It’s election year and yet nobody is talking about this except the Greens. This is the Century of warming, when will it impact politics? I would have thought that all New Zealanders would be alarmed and outraged at the speed with which this is happening, the loss of our physical heritage, but all I can hear is a resounding cultural silence, not much more than a concern about winter skiing. AndyS’ letter is an expression of that constant effort to downplay and trivialise the effect of warming.
I grew up within sight of the Southern Alps, and the thought of the near certain loss of its chill, gleaming ice-caps and primeval glaciers makes my heart ache.
My vote has to go with the climate.

And when precipitation increases – along with temperature – and we have retreating glaciers world wide – then andy there can be only one conclusion – Global Warming.
As the post says –
“Glaciers are large-scale, highly sensitive climate instruments, which in an ideal world we would pick up and weigh once a year, because their fluctuations provide one of the clearest signals of climate change.”

“So increased precipitation and increased temperature would have an unknown net effect on a glacier, depending on the relative impact of each parameter”

Not so. The planet has already experienced increased temperatures and rainfall for about 40 years at least and glaciers have generally retreated so it is clear increasing temperatures are the stronger factor.

Current trends suggest most glaciers will melt completely. Maybe a few large ones at great altitude will partly survive.

There seems to be concern about glacier melt and reduced snow cover in the Himalayas and Andes impacting on water supplies for agriculture and hydro dams.

For any individual glacier, the impact of local changes in precipitation may trump warming – at least until the snow line moves above the nevée – but the decline in NZ and global land ice is clearly related to the heat that’s been accumulation in the climate system. That is certainly down to CO2.

We are still waiting AndyS for your explanation regarding the other factors that are driving the rapid ice melt. If you had followed the links provided, you will have found that globally, net ice loss well exceeds any gains.

Andy the main issue is, that precipitation falling now in a warmer world as rain instead of being stored as accretion on the top of a glacier, will rush of to sea in a matter of days instead of being stored for the warm Summer month to be released gradually and constantly into the rivers.
The result is an aggravation of flash floods versus dry cycles and more of the available precipitation water being unavailable for irrigation when its needed most.
The fact that we might have increased precipitation overall in a warmer world is not at all equal to more water being actually available when and where its needed most. The contrary is the case for those regions that depend on the summer melt flows from glaciers keeping the rivers going trough Summer.

We can Dam rivers – e.g. Wellington’s water supply is mostly from dams on the regions rivershttp://www.gw.govt.nz/live-water-supply/
For Chch the aquifers serve much the same purpose – topped up from the braided rivers.

There is absolutely no question that the glaciers are melting and it is due to the additional CO2 in the atmosphere, put there by the burning of fossil fuels. The glaciers will melt completely and the snow melt will go as well. This will give drought in the late summer and the rivers and streams will dry up. The only part that is uncertain is how long it will take. That what climate change is all about. A changing climate.

The only reason glaciers are melting is because CO2 in the atmosphere is raising the temperature. Its called global warming. You know all this. Co2 is a global warming gas and has raised the average temperature of the world .8C and this is melting the ice. Worse than that it will melt all the ice on Greenland and West Antarctica and raise the sea level 12 to 20 meteres. It might take a bit of time for it all to melt but it will get there.

Imagine if you will, a quaint little village in England, where andy is the village constable. In over 1,000 years of recorded history, every single inhabitant of this village has died of natural causes.

One sunny day, a villager is discovered dead. There’s a knife sticking out of his chest. His wife is sitting beside the body, her hands covered in blood. Her bloody fingerprints are on the handle of the knife, and she is wailing “I’m sorry, I’m sorry” over and over. The couple are renowned in the village for their fiery arguments.

Constable andy comes along, sizes up the scene and says, “Nothing to see here, move along. This man obviously died of natural causes.”

I never actually claimed that the current ice melt was “natural causes”. I merely enquired about the previous warming periods and glacial melt

However, stabbing ones spouse could be considered a “crime passionelle” (in French) where apparently the hot Mistral wind can be a mitigating circumstance in your defence, so indeed these could be considered “natural causes”.

So beware the mad dog Nor’Wester, which is blowing strong in these parts and has (drum roll please) pushed Timaru to its highest July temperature since records began

When your position is based on the rejection of science, all you have left is empty rhetorical games. Bob did not claim that “the current glacial melt is caused by elevated levels of co2″. He said that the glacier melt is caused by the elevated temperatures, which in turn are caused primarily by CO2.

It is pretty clear that temperature plays a dominant role in glacier ice balance. A change in prevailing temperatures – regardless of the mechanism causing that change in temperature – is going to have an impact on glacier size.

The fact that the current (warming) change in temperatures is being driven primarily by anthropogenic GHGs does not preclude the possibility of non-anthropogenic changes in temperature driving past glacier changes, or vice versa.

When you say “This leaves zero reasons for previous periods of glacial melt”, are you claiming that global temperatures never varied prior to the 20th century? I’d like to see your evidence for that.

“Ladies and Gentlemen of the jury, we know from the scientific record that forest fires have burned back and forth across the surface of this planet for eons – certainly well before our species entered the scene, let alone the invention of Mr. Zippy Firelighters – and yet the prosecution would have you believe in this unlikely phenomenon they call ‘Arson’…”

The glaciers melted due to increased levels of CO2 which went from 180 parts per million to 280 parts per million. We are now at 400 parts per million and waiting for the rest of the ice to melt. Read all about it. http://globalwarmingsimplified.weebly.com/

And yet the teara site reports
”
The position of the Franz Josef Glacier has changed since 1865. From 1865 to 1985 it gradually thinned and retreated, with some minor advances. From 1985 to 2006 it generally advanced and thickened, with minor retreats.”

So until 8 years ago, the Franz was advancing, yet the Guardian reports that it has been rapidly retreating for the last 15 years.

Glaciers overall alter the timing of runoff not the total volume. It is true as they begin to recede they can increase flow from the stored ice, but in NZ you are passed that point. Annual precipitation will control overall flow, but summer runoff will decline and spring runoff will increase. An example of rivers with and without glaciers and their response can be seen in the Nooksack River Basin of Washington.http://glacierchange.wordpress.com/2014/05/06/nooksack-river-glacier-runoff-importance/

Mspelto,
Thanks for your interesting blog posts on NZ glaciers.
When isaw your numbers of 15% reduction in NZ glacier volume vs the latest figures of 30% I must say I was somewhat sceptical of the dramatic ice volume loss since 2008

The numbers presented do seem to stack up after I did a few calculator examples, so the real question for me is what caused the dramatic loss,of ice over the last decade? There must be a more nuanced reason than just ” global warming”

There must be some interesting and complex glacier dynamics at play here?

The Aviator

The Aviator is Gareth's latest book -- the first in a series set in The Burning World. Cover artist Dylan Horrocks describes it as: "a light-hearted journey (by state-of-the-art airship) around a world transformed by climate change and subsequent political collapse. Rock God Evangelists, super-rich survivalists, back-to-nature primitivists, heavily armed luddites, goats with the secret of eternal youth, and a horny artificial intelligence with a taste for bluegrass and classic Hollywood films; The Aviator is a Gulliver-esque romp through a future we hope won’t come to pass."